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How to increase horsepower on my truck

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Hi Motor Ops,
Looking to get some more ponies out of my '05 GMC Sierra without spending too much. My goal is to get a little more speed on the lower end.
Level 2 (XP: 250)
12 months ago
Hi Sailor,

If you are working with a stock truck then there is a great amount of improvement that can be done for a relatively low cost.

To attain some extra power I will point you in the direction of our tuning. Your vehicle has three options:
-single power level tune
-DSP2 (two power level) tune
-DSP5 (five power level) tune

I am assuming that you use this vehicle for more than just a work truck because the majority of us do. This is where the DSP5 option really shines because we design the tunes so that you really have a tune for just about any driving situation that you would encounter. Whether you're towing 13,000 LBS or driving across a province or state with the family, the DSP5 tune has an option that will deliver results.

If you are using your truck as a daily driver as well as a work truck then our goal, as usual, is reliability and drivability. My recommendation is, with the addition of tuning, you attack the flaws in the factory design.

The 2004.5 to 2005 Duramax trucks have two major flaws in their design at a factory power level.
-A highly restrictive turbo mouth piece
-A very small EGR cooler

I have seen a lot of factory trucks absolutely starving for air because of the factory turbo mouthpiece. The factory mouthpiece creates a vacuum like effect on the turbo which leads to in turn leads to high EGTs and engine overheating.

The solution:

-S&B makes an aftermarket turbo mouth piece that fits perfectly into place. It will dramatically improve the overall operation of your vehicle and the cost is very reasonable.
-An alternative solution is a DIY LBZ induction kit. I have seen many people take an LBZ turbo mouthpiece and fit it up to the LLY turbo and then reconstruct the intake tubing to fit correctly. If you can find the parts at a wreckage yard to do this you may be able to do it for a little less than the S&B intake but it will take a little bit of time to find the parts.

Now onto the EGR...

The LLY engine is the first RPO duramax to come into full production with an EGR (LB7 trucks that are rated for California emission were also equipped with an EGR, but there aren't many). Being that it it was the first RPO equipped with an EGR you are bound to have issues. The EGR design is way too small to properly handle the exhaust volume and temperatures that flow through it.... ever wonder why LLYs are so prone to head gasket issues? I think we're onto something here.

Anyways the fact is that if you still have your EGR intact and flowing you really should get it either blocked or removed to save your self from future headaches and money in repairs.

The solution:
-EGR blocker plate. Just as the name says it blocks the exhaust gas from entering the EGR inlet. The cost is usually between $10 and $15 but the installation can be a little bit of a pain due to the location of the EGR riser.
-Y-Bridge kit or EGR delete is your alternative solution. This will completely remove the EGR from the truck and you no longer have to worry about a ruptured EGR sending coolant into your engine or any exhaust ever reaching the intake of your truck. It comes with a bit of a price but man does it look great and you wont believe how much it drops EGTs and how much faster your turbo will spool up. In my experience I have seen EGTs drop 150 degrees at WOT with a Y-bridge kit.

With the three mods I discussed (DSP5 tuning, Turbo mouthpiece, and EGR removal or block) you should have a vehicle that you can rely on every day and will be an absolute pleasure to drive. Let us know if we can help you with any other questions!


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